This definition appears very rarely
Samples in periodicals archive:
Abstract: The use of the manned orbit transfer vehicle (MOTV) for support of future space missions is defined. Some 20 generic missions are defined each...
The requirements for geosynchronous orbit capability using the manned orbit transfer vehicle (MOTV) are defined.
least two main engines will be needed for a manned Orbit Transfer Vehicle. However, this heuristic approach of specifying redundancy doesn't resolve